The proposed research is a study of an inherited hemolytic anemia ("xerocytosis") in which red blood cells leak potassium, are dehydrated, and maintain low intracellular 2,3-DPG despite the anemia, a normal intracellular pH, and an absence of any known defect in metabolism. Xerocyte membranes will be characterized to define the molecular basis for abnormal function. Parameters of characterization will be high-resolution analytic fractiona- of membrane proteins, accessibility to surface labeling reagents, pattern of protein cross-linking, content of membrane-associated enzymes, and capacity to reseal. Metabolism in xerocytes will be examined, with emphasis on reactions involved in maintenance of 2,3-DPG. Kinetic parameters of key enzymes, levels of metabolic intermediates, flux of radiosotope tracers through 2,3-DPG, and cation effects on reaction rates will be studied. Aspects of membrane-cytoplasm interaction will be investigated, with emphasis on identification of factors responsible for elevated retention of glyceraldehyde-3-phosphate dehydrogenase in xerocyte membranes. Effects of normal and xerocyte cytoplasm on ghost resealing will be studied. Studies of red cell membrane biogenesis in bone marrow cultures will be undertaken, with the objective of describing stages of membrane protein synthesis and identifying the time of earliest expression of altered membrane structure and function in xerocytosis.